Nord L. Gale

Elevated immunoglobulin E (IgE) levels in children with exposure to environmental lead

Lead has been reported to be an immunosuppressive agent in animal systems at levels far below those recognized as overtly toxic. Little data exist on leads effects on the human immune system, especially in young children who are at greatest risk for exposure to this environmental hazard. The effects of environmental lead exposure on the human immune system were examined in a population of young children, age 9 months-6 years, from the urban population of Springfield-Greene County, Missouri. Reported here are data from 279 children with blood lead levels ranging from 1 to 45 microg/dl. White blood cell populations have been enumerated and examined for cell surface expression of activation markers. Serum has been analyzed for IgE, specific titers to Rubella vaccine, sCD25 (the soluble form of the IL2 receptor), sCD27 (the soluble form of the lymphocyte specific member of the tumor necrosis factor receptor family), and IL4 (the cytokine interleukin 4). Variation of these assays with age of the child was considered in statistical analysis of data. A statistically significant relationship of IgE and blood lead level was found in this population; as blood lead (PbB) level increases, IgE level increases. No other statistically significant differences between risk categories or other associations with blood lead level were found. The exact mechanism for this apparent stimulus of IgE-producing B cells remains to be elucidated. The development of allergic symptoms is often preceded by an increase in IgE. These data indicate that ingested lead could play a role in this process by stimulating IgE production.

Lead, Zinc, Copper, and Cadmium in Fish and Sediments from the Big River and Flat River Creek of Missouri's Old Lead Belt

The Old Lead Belt of Missouri was a major lead-producing region for over a century. Several large tailings piles and other industrial wastes remain behind, though mining operations in the region ceased in 1972. Samples of stream sediments and fish were collected from established sites on the Big River and Flat River Creek over a 3-year period from 1998 to 2000 to evaluate ongoing remediation efforts and determine the current impact of residual mining wastes. Benthic sediments and fish taken in the vicinity of inactive industrial sites were found to contain elevated concentrations of Pb, Zn, Cu, and Cd. Concentrations of Pb and Zn in fillets of suckers and sunfish, as well as in whole bodies of sunfish, correlate well with metal concentrations observed in surficial sediments. The results of analyses provide valuable quantitative information regarding specific sources, current levels of contamination, potential risk to public health, and will allow more accurate assessment of continuing remediation efforts.

Evaluation of Toxicity, Bioavailability and Speciation of Lead, Zinc and Cadmium in Mine/Mill Wastewaters

The toxicity of common compounds of lead, cadmium and zinc was evaluated in waters similar to that found in the world’s largest lead producing area in Missouri. Static, acute toxicity tests were pe...

Fish from Missouri's lead belt: To eat or not to eat

Data collected over the past four years indicate that filets of suckers and some species of sunfish taken from certain sites in Missouris Old Lead Belt consistently contain elevated lead concentrations which exceed the limit of 0.3 μg/g suggested by the World Health Organization. The problem exists in bottom-feeding species taken from some sites along the Big River affected by erosion from abandoned lead tailings piles. Fish from many other sites within the Old Lead Belt and the New Lead Belt, including current wastewater treatment systems, are within the acceptable limits for lead in food. Public health implications are discussed relative to observed lead concentrations and available data regarding lead toxicity to humans.

Immunity in children with exposure to environmental lead: I. Effects on cell numbers and cell-mediated immunity

Studies conducted in animal systems have shown that lead is an immunosuppressive agent at levels far below those causing overt toxicity. Children less than six years of age are the population at highest risk for exposure to environmental lead; however little data were available to assess effects on the developing immune system in this age group. Reported here is the completed Phase I study on 193 children, ages 9 months to 6 years, with blood lead levels from 1 to 50 (μg dL−1, recruited from the urban population of Springfield-Greene County, Missouri, through their participation in the WIC (Women, Infants, and Children) and Lead Poisoning Prevention Programs. This portion of the study dealt with enumeration of cells involved with the immune response andin vitro mitogenic stimulation of lymphocytes. The percent lymphocytes, monocytes, granulocytes, T cells (total), B cells, CD4+Ts and CD8+Ts and CD4+/CD8+ ratios were determined and the data were analysed. No consistent significant differences were seen among the various risk categories currently identified by the CDC. Though two age groups showed some possible effect of lead, none of the various cellular parameters within these age groups showed significant correlation with blood lead. The lymphocyte response toin vitro mitogenic stimulus was studied on 42 children (including 17 in risk classifications IIA and higher) using the mitogens phytohemagglutinin (PHA), Concanavalin A (Con A), and Pokeweed mitogen (PWM). No consistent statistically significant differences were seen among the various risk categories; the effects of lead, if present, are most likely subtle and obscured by the interindividual and time-dependent variation inherent in this type of study.

Immunity in children with exposure to environmental lead: II. Effects on humoral immunity

Lead has been found to depress the immune system in animal studies at levels far below those responsible for overt toxicity. Literature studies in animal systems most clearly showed an effect of lead on response to a specific immunogenic stimulus. Data are sparse concerning the effects of lead on the immune system in the human population at greatest risk for exposure-children up to six years of age. This portion of the Phase I study reports concentrations of IgG, IgM, IgA, and IgE, as well as antibody titers to the specific antigenic stimuli provided by the vaccines against diphtheria, tetanus, and Rubella. The study population consisted of a group of 193 children, ages 9 months to 6 years, who participate in the WIC (Women, Infants and Children) and Lead Poisoning Prevention Programs in the urban area of Springfield-Greene County Missouri. Blood lead levels ranged from 1 to 50 μg dL−1. Total Ig levels were determined and the data were analysed. No consistent significant differences were observed among the risk categories in the five age groups examined. A single Ig class in each of three age groups showed apparent significant differences among the various risk categories, but these differences were not correlated with blood lead. An analysis of specific antibody titers to diphtheria, tetanus, and Rubella was performed. Regression analyses of current data in Phase I of this study suggest a detrimental effect of lead on the antibody titres to diphtheria and Rubella.